Girls' Generation originally debuted as a nine-member group in 2007. Jessica left the group in 2014, while Seohyun, Tiffany and Sooyoung left the group's agency, SM Entertainment, in October. The agency announced plans for a new unit in August.

Girls' Generation is known for such singles as "Run Devil Run," "The Boys" and "Party." The group last released the album Holiday Night in August 2017 prior to Seohyun, Tiffany and Sooyoung's departures.